Electrophotographic copier with removable drum

ABSTRACT

A XEROGRAPHIC CARRIER IS MOUNTED IN A HOUSING FOR TRAVEL IN A PREDETERMINED DIRECTION AND HAS AN EXPOSED PHOTOCONDUCTIVE LAYER WHICH IS ADAPTED TO BE UNIFORMLY CHARGED IN PREPARATION FOR TRANSFER OF LATENT IMAGES TO THE LAYER. THE CARRIER CAN BE WITHDRAWN FROM THE HOUSING IN A PREDETERMINED PATH. IT IS USUALLY A DRUM MOUNTED ON A STATIONAR SHAFT IN THE HOUSING. A DEVELOPER DEVICE IS MOUNTED IN THE HOUSING AND CAN MOVE SUBSTANTIALLY RADIALLY OF THE DRUM BETWEEN A POSITION ENGAGING THE DRUM FOR DISCHARGING ONTO THE SAME ELECTROSTOPC DEVELOPER MATERIAL WHICH FORMS ON THE CHARGED LAYER POWER IMAGES, AND A WITHDRAWN POSITION REMOTE FROM THE CARRIER. A CLEANING DEVICE IS ALSO PROVIDED WHICH CAN SIMILARLY BE MOVED RADIALLY OF THE DRUM BETWEEN A POSITION ENGAGING THE LATTER AND REMOVING RESIDUAL ELECTROSCOPIC DEVELOPER MATERIAL FROM THE LAYER AND A RADIALLY WITHDRAWN POSITION. A MOVING ARRANGEMET IS PROVIDED FOR MOVING ONE OR BOTH OF THESE DEVICES BETWEEN THEIR RESPECTIVE POSITIONS. THE MOVING ARRANGEMENT INCLUDES A PIVOTING CRANK AND A LEVER FOR PIVOTING IT LOCATED ADJACENT TO THE ACCESSIBLE END OF THE DRUM. WHEN THE MOVING ARRANGEMENT IS IN A LOCATION IN WHICH THE ONE OR BOTH DEVICES ARE IN THEIR OPERATING POSITIONS, THE LEVER WILL BLOCK WITHDRAWAL OF THE DRUM FROM THE HOUSING.

June 6, 1972 H. ENGEL ET'AL 3,667,840 v El:ECTROII'IOTOGRAPHIC COPIER WITH REMOVABLE DRUM ild Dec.

2 Sheets-Sheet l INVENTOR HERBERT ENGEL BY KARL HARTWIG GUNTER SCHNALL 44-114"! fi ll-AV Allan,

June 6, 1972 ENGEL ETAL EIJHUTROPUQTOGRAPIIIC GOPIER WITH REMOVABLE DRUM 2 Sheets-Sheet 2 Filed Dec. 10, 1970 Qm m mm vm. mw Q 8 8 as INVENTOR HERBERT ENGEL y KARL HARTWIG GUNTER SCHNALL 4,101 Eat r United States Patent F US. Cl. 355-3 Claims ABSTRACT OF THE DISCLOSURE A xerographic carrier is mounted in a housing for travel in a predetermined direction and has an exposed photoconductive layer which is adapted to be uniformly charged in preparation for transfer of latent images to the layer. The carrier can be withdrawn from the housing in a predetermined path. It is usually a drum mounted on a stationary shaft in the housing. A developer device is mounted in the housing and can move substantially radially of the drum between a position engaging the drum for discharging onto the same electroscopic developer material which forms on the charged layer powder images, and a withdrawn position remote from the carrier. A cleaning device is also provided which can similarly be moved radially of the drum between a position engaging the latter and removing residual electroscopic developer material from the layer and a radially withdrawn position. A moving arrangement is provided for moving one or both of these devices between their respective positions. The moving arrangement includes a pivoting crank and a lever for pivoting it located adjacent to the accessible end of the drum. When the moving arrangement is in a location in which the one or both devices are in their operating positions, the lever will block Withdrawal of the drum from the housing.

BACKGROUND OF THE INVENTION The present invention relates generally to electrophotographic copiers, and in particular to improvements in xerographic copiers.

Xerographic copiers usually utilize a xerographic plate in form of a drum provided on its outer periphery with a layer of photoconductive material. The drum is rotated and in so doing the layer sequentially passes past certain operating stations where it is first charged, whereupon a latent image is transferred to the layer which is subsequently developed by dusting pulverulent electroscopic developer material onto the layersuch material also being known as a tonerwhere it adheres at selected portions depending upon the charging and the previously transferred latent images. Subsequently the powder images which are thus formed on the layer are transferred to a copy sheet and the layer is then cleaned of residually adhering electroscopic material before it is recharged for the next copying process.

The xerographic drum in such devices is removable from the housing for certain purposes, namely inspection, repair, replacement and/or such cleaning which is not effected by the cleaning device. If this removal is carried out while the developer device supplying pulverulent electroscopic developer material to the layer, and/ or the cleaning device cleaning the layer of residual developer material, are in their respective operating positions, the

devices or components thereof may be damaged, and damage may also occur to the 'very delicate photoconductive layer on the xerographic drum and with which layer the devices are in contact when in their operating position.

3,667,840 Patented June 6, 1972 SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to provide a novel and improved xerographic copier which is not possessed of the disadvantages mentioned above.

More particularly it is an object of the present invention to provide such an improved xerographic copier in which removal of the xerographic carrier from the housing is blocked while the developer device and/or the cleaning device are in their respective operating positions.

A concomitant object of the invention is to provide such an improved xerographic copier which has novel and very simple means for blocking the withdrawal of the xerographic carrier from the housing while the developer device and/or the cleaning device are in their respective operating positions.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of the invention resides, in an electrophotographic copier, in a combination comprising a housing and a xerographic carrier mounted in the housing for travel in a predetermined direction and having an exposed photoconductive layer adapted to be uniformly charged precedent to transfer of latent images to the layer, with the carrier being withdrawn from the housing in a predetermined path.

A developer device is mounted in the housing for movement between a first withdrawn position remote from the carrier and a first operating position in which it engages the travelling carrier for the purpose of applying pulverulent electroscopic developer material to the layer with resultant formation of powder images on the latter. Transfer means transfers such powder images onto a copy sheet.

A cleaning device is arranged downstream of the transfer means mounted in the housing for movement between a second withdrawn position remote from the carrier and a second operating position in which it engages the carrier for cleaning residual pulverulent developer material from the layer.

Finally, there is provided moving means for moving at least one of these devices between the aforementioned positions thereof, and this moving means is displaceable between one location in which the one device is in its withdrawn position and another location in which the one device is in the aforementioned operating position thereof and in which the moving means blocks withdrawal of the carrier from the housing.

Of course, it will be appreciated that advantageously the moving means will move both of the devices in the above-indicated manner and in that case the withdrawal (and, of course, the insertion) of the xerographic drum is naturally greatly simplified because a simple operation of the moving means is sufficient to displace both devices to 7 their withdrawn positions to permit withdrawal of the xerographic drum, and subsequently after insertion of the xerographic drum, to place them into their respective operating positions.

This avoids, obviously, any necessity for separate blocking devices for blocking the withdrawing of the xerographic drum when the developer and cleaning devices are in their operating positions, and thus greatly simplifies the construction of a xerographic copying apparatus.

Advantageously both the developer device and the cleaning device are shiftable substantially radially of the xerographic drum and connected with leakage rods which are pivoted to the moving means so that upon operation of the moving means, the devices are displaced via the respective linkage rods. The cleaning device may in conventional manner comprise a cleaning tape or paper or another suitable material which is convoluted about a supply roller from which it is withdrawn incrementally and taken up on a take-up roller. A spring-biased or otherwise biased pressure roller incrementally presses the cleaning tape into engagement with the photoconductive layer on the xerographic drum when the cleaning device is in its operating position. The pressure roller is connected with the moving means so that upon operation of the latter, the pressure roller is moved out of position in which it presses the cleaning tape against the layer on the xerographic drum.

It is advantageous to make the developer device completely removable from the housing of the novel copier, for instance for inspection or replenishment of the electroscopic developer material a supply of which is accommodated in the developer device. The removal of the developer device is particularly simple if the device is provided with supporting rollers which in the operating position of the developer device engage the peripheral surface of the Xerographic drum so that when the developer device is moved to operating position it will automatically be properly located with respect to the drum. The linkage rod which serves to displace the developer device radially with reference to the drum between its operating position and withdrawn position advantageously is provided with biasing means which acts via the linkage rod upon the developer device "in a sense biasing the supporting rollers into engagement with the peripheral surface of the drum when the developer device is in operating position. It is also advantageous to provide in a stationary component ofthe copier, for instance in the housing, a slot which is elongated and inclined with reference to the direction of radial displacement of the developer device, and to provide a pin or analogous projection on the linkage rod which is guided in this slot and which, when the developer device approaches its operating position, cooperates with an abutment on the developer device preventing withdrawal of the latter from the housing, whereas when the developer device is in its withdrawn position, the projection disengages from the abutment and permits withdrawal of the developer device from the housing. This is a particularly simple construction because the developer device is thus freed for entire withdrawal from the housing by operation of the moving means which moves it from its operating position to its withdrawn position. Furthermore, this moving means may as already pointed out above, also be the instrumentality by means of which the cleaning device is displaced from operating position to withdrawn position and which blocks or permits withdrawal of the xerographic drum from the copier.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention iself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is ta vertical somewhat diagrammatic sectional view of a copier emodying the present invention with the developer device and the cleaning device in operating position; and

FIG. 2 is a view similar to FIG. 1 but illustrating the apparatus of FIG. 1 with the developer device and the cleaning device in withdrawn .position preparatory for withdrawal of the xerographic drum from the housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail it will be seen that reference numeral 1 generally identifies a housing of an electrophotographic copier whose overall configuration is of no importance for purposes of the invention. Mounted in the housing is a shaft 2 onto which a xerographic drum 3 can be placed so as to be removably journalled thereon for rotation. The drum 3 is provided in known manner with a photoconductive layer on its outer peripheral surface. The drum 3 is driven in rotation in suitable manner also known to those skilled in the art, for instance by interengagement of gears provided on the drum and on the housing 1 which in turn are driven by a non-illustrated drive, and turns in the illustrated embodiment in counterclockwise direction. It is retained in position on the shaft 2 against axial displacement thereon by a nut 57 which is threaded onto an end portion of the shaft 2 provided for this purpose.

In known manner the drum 3 is surrounded by a plurality of devices or operating stations. 'Ihus, reference numeral 11 identifies a known corona charging device which charges the photoconductive layer on the travelling drum 3. Downstream of the device 11-as seen in the direction of rotation of the drum 3there is arranged an exposure device which serves to transfer latent images to the photoconductive layer. The exposure device comprises a lens or objective 4, a stationary reflector 5 and movable refiectors 6, 7 and 8. It further comprises light sources 9 and a transparent supporting plate 10 on top of which an original to be copied (not shown) is to be supported with the side to be copied facing downwardly. The light sources 9 may be mounted in a carriage which can move along and underneath the component 10. After the device 11 has effected uniform charging of successive increments of the photoconductive layer on the drum 3 to a predetermined potential, the thus-charged increments thereupon travel past the exposure station or device at which an image of the original supported on the support 10 is projected via the reflectors 8, 7, 6, the lens 4 and the reflector 5 onto the successive increments of the photoconductive layer. On this layer the thus-projected light produces a latent image of the original, which image is developed as the photoconductive layer travels past another operating station, a developing station or device 12. The developing device 12 comprises a container 25 containing a quantity of pulverulent electroscopic developer material, also known as toner, with the container 25 being provided in its lower portion with apertures 26a through which a revolving dispensing device 26 dispenses controlled quantities of the toner powder, as it will hereafter be called for the sake of convenience so that they fall in the illustrated manner onto the scoops of a scoop conveyor 24. The conveyor 24 as well as the device 26 are driven in non-illustrated manner, for instance by individual drives or by connection with the main drive of the copier, and the toner on the scoops of the scoop conveyor 24 is conveyed in clockwise direction upwardly for discharge from the upper end of the conveyor 24 onto the surface of the layer on the rotating drum 3. The thus-discharged electroscopic material or toner powder adheres to selected portions of the photoconductive layer to form thereon a powder image. Excess toner powder falls onto the inclined casing portion 12a of the device 12 and slides to the lowermost point where it can be engaged by the advancing scoops of the scoop conveyor 24 as illustrated.

As the drum 3 continues to rotate in counter-clockwise direction the powder image produced on the photoconductive layer moves past a transfer corona device 13 of known construction where it is transferred onto a copy sheet 17 supplied from a stack 20 resting on a pivoted spring-loaded supporting table 19 and supplied to the space between the device 13 and the photoconductive layer on the rotating drum 3 by transport rollers 21 and 22. After transfer of the powder image to the copy sheet 17 the latter now carrying the finished copy is advanced to the discharge table 23. Release of the copy sheet is effected by the discharge corona device 15 which permits release of the sheet from the drum. Because upon continued rotation of the drum 3 the layer will again move past the corona charging device 11, and because some residual quantities of the toner powder will inevitably adhere to the photoconductive layer, there is provided downstream of the device 15 and upstream of the device 11 a cleaning device 16 which serves to remove the residual toner powder. Its construction will be discussed subsequently.

Returning to the device 12 it is pointed out that it is guided in the housing 1 by means of rails 27 and 28 which engage with guide rails 29 (one shown) provided for this purpose and which permit the device 12 to move in direction substantially radially of the xerographic drum 3 from its operating position as shown in FIG. 1 to its withdrawn position shown in FIG. 2. When the device 12 is in the operating position shown in FIG. 1, the supporting rollers 3 and 31 provided for this purpose on the device 12 contact the peripheral surface of the drum 3 so that whenever the device 12 has been withdrawn to the position shown in FIG. 2 and is subsequently returned to operating position as shown in FIG. 1, a precise predetermined location of the upper discharge end of the scoop conveyor 24 with reference to the photoconductive layer on the peripheral surface of the xerographic drum 3 is automatically obtained without having to provide any adjustments. The device 12 can further be withdrawn beyond the position shown in FIG. 2, by continuing to move it along the guide rails 29 so that it can be withdrawn to the exterior of the housing 1 for replenishment of the toner powder in the container 25, for inspection purposes, for cleaning purposes or the like.

As already pointed out, there is also provided the cleaning device 16. This device, also, can be withdrawn in analogous manner from the housing 1 after a nonillustrated locking arrangement is released, simply by gripping the handle 33 and exerting pull thereon. This is for the purpose of inspecting the device 16 if necessary, and also for replacing the soiled cleaning tape 32 with a new one, or for correcting a malfunction. The cleaning tape may consist in known manner of paper or the like and is supplied on a supply roller 35 about which it is convoluted and from which it is incrementally withdrawn to be wound onto a take-up roller 34. The latter is driven in non-illustrated manner, for instance by connection in a suitable way with the main drive of the electro-photographic copier. The tape 32 is maintained taut by being trained about guide rollers 37 and 38 and by being pressed against-the periphery of the rotating drum 3-and thereby against the photoconductive layer thereon-by a biased pressure roller 36 which is mounted on an arm 39 pivotable about the axis of the guide roller 37. A tension spring 40 has one end connected to the housing 1 or another stationary component of the copier and other other end secured to the portion 39a of the arm 39 to thereby act upon the same in a sense pressing the pressure roller 36 against respective increments of the tape 32 whereby these increments are pressed against the photoconductive layer on the travelling drum 3.

In accordance'with the present invention a pin or projection 42 is provided on a linkage rod 33 and is guided in an elongated slot 41 of the housing 1. The portion 39a of the arm 39 engages with the pin 42 and the linkage rod 43 is pivoted to a crank 44 which is mounted for turning movement on 'an axis 45 secured to a stationary component of the copier, for instance the housing'l.

A moving or operating lever 46 is mounted on the shaft 45 and located exteriorly of the housing '1, being provided with a handle 47. Turning of the lever 46 and thereby of the crank 44 elfects displacement of the arm 39 in clockwise direction counter to the action of the spring 40, so that the pressure roller 36 is thereby withdrawn from engagement with the drum 3. According to the invntion the lever 46 is so mounted that at least portions thereof extend into the path which the drum 3 or portions thereof must traverse when the drum 3 is to be withdrawn from the housing 1 and from the shaft 2. Evidently, this path is parallel to the shaft 2. It follows, therefore, that the drum 3 can be withdrawn from the shaft 2 only when the lever 46 has been operated in a sense causing the pressure roller 36 to be withdrawn from contact with the drum 3 so that it no longer presses increments of the cleaning tape 32 against the drum 3. This makes it impossible to withdraw the drum 3 while such engagement exists, and avoids the danger of damage to the cleaning tape 32 and, even worse, of damage to the highly delicate photoconductive layer on the peripheral surface of the drum 3.

On the other hand, however, the cleaning device 16 can be removed at any time and irrespective of the position of the lever 46 or of the pressure roller 36, simply due to the fact that there is the contact between the portion 39a of the arm 39 and the pin 42, so that whenever it is desired to withdraw the device 16 for inseptction, replacement of the tape 32 or for other reasons, this can be carried out Without having to consider any other components of the copier and without having to accept the danger that harm might come to such components.

Also connected to the crank 44 is an additional linkage rod composed of a portion 53 which is pivoted to the crank 44 and a portion 50 which is provided with a pro jection or pin 49. The adjacent end portions of the por-- tions 50 and 53 are connected in that the portion 50 is provided with a slot 50a extending longitudinally thereof and the portion 53 is provided with two pins 51 and 52 received in the slot. A tension spring 55 is connected to the pin 51 and an additional pin 54 provided for this purpose on the portion 50. Thus, the tension spring 55 tends to draw the portions 50 and 53 together and to shorten the length of the linkage rod composed of the portions 50 and 53. The pin 49 is guided in an inclined slot 48 formed in the housing 1 for this purpose and engages with an abutment 12b provided on the device 12.

If the device 12 is in the position shown in FIG. 2 and the lever 46 is operated in a sense moving it towards the drum 3 to operating position, in which the supporting rollers 30 and 31 will engage the peripheral surface of the drum 3, pin 49 will be in engagement with an abutment 12c and if the length of the linkage rod composed of the portions 50 and 53 is properly selected, the spring 55 will act upon the supporting rollers 30 and 31 during the terminal portion of the movement from the position of FIG. 2 towards the position of FIG. 1 in a sense biasing the rollers 30 and 31 against the periphery of the drum 3. Thus, it is assumed that independent of manufacturing tolerances existing in the components 44, 50 and 53 the device 12 will always assume an exactly predetermined position with reference to the drum 3 whenever the device 12 is moved to operating position, this predetermined position being determined by the engagement of the rollers 30 and 31 with the drum 3.

As a comparison of FIGS. 1 and 2 shows, the arrangement and inclination of the slot 48 is such that when the device 12 approaches its right-hand end position shown in FIG. 1, the pin 49 will extend into the path of the abutment 12b which is determined by the guide rails 29, whereas in the left-hand end position shown in FIG. 2 the pin 49 will be located above the path of the abutment 12c and will not contact the same. Thus, when the device 12 has been moved to the withdrawn position shown in FIG. 2 by means of the lever 46, it can be further withdrawn out of the housing 1 without having to be decoupled or without having to be disconnected in any further way. This means that movement of the device 12 from the position of FIG. 1 to the position of FIG. 2 by means of the lever 46 automatically releases the device 12 for further withdrawal beyond the position of FIG. 2 outwardly of the housing 1 and thus greatly simplifies the access to the device 12.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

When the invention has been illustrated and described as embodied in an electrophotographic copier, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In an electrophotographic copier, in combination, a housing; a xerographic carrier mounted in said housing for travel in a predetermined direction and having an exposed photoconductive layer adapted to be uniformly charged precedent to transfer of latent images to said layer, said carrier being withdrawable from said housing in a predetermined path; a developer device mounted in said housing for movement between a first withdrawn position remote from said carrier, and a first operating position engaging the travelling carrier for applying pulverulent electroscopic developer material to said layer with resultant formation of powder images on the latter; transfer means for transferring such powder images onto a copy sheet; a cleaning device downstream of said transfer means and being mounted in said housing for movement between a second withdrawn position remote from said carrier, and a second operating position engaging said carrier for cleaning residual pulverulent developer material from said layer; and moving means operatively associated with at least one of said devices for moving the same between said positions thereof, said moving means being displaceable from a first position in which it extends into said path and blocks removal of said carrier and in which said at least one device is in the operating position thereof, to a second position in which said moving means is retracted from said path and said at least one device is located in the withdrawn position thereof.

2. In an electrophotographic carrier as defined in claim 1, said moving means in said one location being spaced in said path, and in said other location extending at least in part across said path.

3. An electrophotographic carrier as defined in claim 1, wherein said moving means is connected with and operative for moving both of said devices between said positions thereof, and wherein said moving means is displaceable between said one location in which both of said devices are in the respective withdrawn positions, and said other location in which both of said devices are in the respective operating positions thereof.

4. An electrophotographic carrier as defined in claim 1, wherein said carrier is a drum; and further comprising a shaft mounted in said housing for rotatably journalling said drum.

5. An electrophotographic carrier as defined in claim 4, further comprising guide means mounting said vdeveloper device for movement substantially radially of said drum between said first positions; and wherein said moving means comprises a displaceable actuating portion and a linkage portion pivoted to said actuating portion and connected with said developer device for moving the latter between said first positions in response to displacement of said actuating portion. T

6. In an electrophotographic carrier as defined in claim 5, said developer device comprising support rollers arranged to engage the peripheral surface of said drum when said developer device is in said first operating position thereof so as to steady said developer device and predetermine the spacing thereof from said layer. 1

7. An electrophotographic carrier as defined in claim 6, and further comprising biasing means connected with said linkage rod and operative for biasing said support rollers into engagement with said layers.

8. In an electrophotographic carrier as defined in claim 4, said cleaning device comprising support rollers, a cleaning tape trained about said support rollers, and a springloaded pressure roller for pressing said cleaning tape incrementally against said layers; and wherein said moving means comprises a displaceable actuating portion and a linkage rod between the same and said pressure roller for moving the same and said cleaning tape away from said layer in response to displacement of said actuating portion.

9. In an electrophotographic carrier as defined in claim 8, said cleaning device further comprising a pivot arm mounting said pressure roller for biased engagement with said tape in a sense pressing increments thereof against said layer; and wherein said linkage rod is connected with said pivot arm for pivoting the same in response to displacement of said actuating portion.

10. In an electrophotographic carrier as defined in claim 5, said linkage portion being elongated substantially in the direction of movement of said developer device and comprising a projection; said developer device comprising an abutment positioned for engaging said projection in a sense preventing withdrawal of said de veloper device from said copier when said developer device approaches said first operating position, and for disengaging said projection in a sense permitting withdrawal of said developer device .whenthe latter approaches said first withdrawn position; and further comprising a slot in a stationary component of said copier inclined to the direction of movement of said developer device and guiding said projection.

References Cited UNITED STATES PATENTS 6/1965 Eichorn 355--15 6/1965 Hunt 355-3 X US. Cl. X.R. SSS-15 

